What: An interlayer is the application of a membrane on distressed pavement surfaces before applying a pavement preservation surface treatment. There are a variety of commercially available materials and techniques, including non-woven geotextile fabrics, non-woven fiberglass/polyester mats, paving grids (made from materials ranging from plastics to chain metal), asphalt rubber chip seals, polymer modified asphalt chip seals, polymer scrub seals, micro surfacing, highly polymer modified ultrathin fine aggregate hot mix interlayers, fiber/polymer asphalt/aggregate blends, and composites of the materials listed above. The interlayer may then be covered with most available pavement preservation surfaces, from chip seals to thin HMA overlays, with the choice determined by the type of interlayer, traffic, climate and type of pavement. Some interlayers are referred to as Stress-Absorbing Membrane Interlayers (SAMIs).

Where: Interlayers have been used successfully on flexible (asphalt) and rigid (Portland Cement Concrete) pavements with moderate to high severity surface cracking caused by surface oxidation and aging. They may also be indicated for hot mix asphalt overlays on jointed concrete to prevent reflective cracking from the joints. Candidates should have a sound pavement structure with good drainage.

Why (advantages): Interlayers are designed to mitigate reflective cracking, prevent surface water from penetrating into the pavement structure, relieve stresses and increase fatigue life. Some interlayers will also allow for a reduction in thickness of the proposed overlay by providing stress and/or strain relief for the subsequent surface treatment. Interlayers can help the new pavement surface last longer and provide a smoother ride throughout the life of the pavement. They reduce cracking and reduce needed future maintenance, providing lower life cycle costs while preserving pavements.

Why not (disadvantages): Costs for the various products vary greatly; some can be costly. Some products may prevent future recycling of the pavement, but newer products have answered those concerns. Interlayers are not designed to address rutting, bleeding, pumping or structural problems.

Bergkamp was elected president at FP2’s board meeting in January 2019 and will serve a two-year term. He’s president and CEO of Bergkamp Inc., Salina, Kan., and succeeds Andrew Crow, Vice President, Pavement Technologies, Ingevity.

“I look forward to serving this organization and its contributors, and working with the surface transportation community to advance pavement preservation,” Bergkamp said. “We bring a host of solutions to the infrastructure problems the country faces, and together we can help the road network live up to its potential of safety, smoothness and reliability. I encourage stakeholders in the pavement preservation community to please join us in this effort, both financially, and through personal efforts.

The Sorenson Award is presented by FP2 Inc. to recognize superior pavement preservation practice, usually to a city, township, county or state agency. The deadline for entries for the year 2018 is June 1, 2019.

At its meeting in March 2018, the Association of Asphalt Paving Technologists (AAPT) held a special, three-hour symposium on Pavement Preservation. The symposium featured five speakers with panel discussion, and Andrew Braham, Ph.D., University of Arkansas-Fayetteville, and Phil Blankenship, Blankenship Asphalt Tech and Training, PLLC, presided. Questions can be submitted by Tweeting to: #AAPT2018

The Ohio Department of Transportation (ODOT) is the winner of the 2016 James B. Sorenson Award for Excellence in Pavement Preservation.

The Sorenson Award is presented each year by FP2 Inc. to recognize superior pavement preservation practice, usually to a city, county or state agency. It was presented this year to Patrick Bierl, design engineer, and Eric Biehl, P.E., asphalt materials engineer, Ohio DOT at an awards luncheon Oct. 13 during the 2016 National Pavement Preservation Conference in Nashville.